1. Field of the Invention
The invention relates to a writing instrument in the form of a ball point pen with two cartridges. More particularly, the invention relates to a ball point pen wherein one of two cartridges can be alternately moved into the writing position by rotating the barrel. The mechanism that moves the cartridges allows a space in the rearward part of the barrel for accommodating or receiving various accessory devices such as stamping mechanisms, marker pens, or the like.
2. Description of the Prior Art
With the writing instruments with multi-color cartridges known to date, in particular two-color cartridges, the alternating mechanism had to be located in the top or rearward part of the barrel. Thus, it was not possible to install additional accessories such as stamping mechanisms, marker pens, etc., adapted to be flipped out in the top part of the pen. A stamping mechanism of this type is disclosed in U.S. Pat. No. 4,606,665.
The present invention is intended to solve this problem by creating a writing instrument in which the mechanism for alternately moving the two-color cartridges into the writing position can be accommodated in the center or bottom part of the barrel. This permits the creation of a space in the top part of the writing instrument for accommodating the above-mentioned accessory devices. In addition, the mechanism for alternating the writing cartridges is designed in such a way that it can be easily dismantled without damage.